hello, that's probably adware. please go to ''firefox > addons > extensions'' & remove it and any suspicious entries (things that you have not installed intentionally, don't know what purpose they serve, etc). <br>also go to the windows control panel / programs and remove all toolbars or potentially unwanted software from there. <br>finally, run a full scan of your system with different security tools like the [http://www.malwarebytes.org/products/malwarebytes_free free version of malwarebytes] & [http://www.bleepingcomputer.com/download/adwcleaner/ adwcleaner]. [[Remove a toolbar that has taken over your Firefox search or home page]] [[Troubleshoot Firefox issues caused by malware]]

Note that your System Details List shows the Yoono 7.7.29 extension *http://kb.mozillazine.org/Preferences_not_saved